A protestor's placard is seen placed on top of a direction sign pointing to a site run by Cuadrilla Resources outside the village of Balcombe in West Sussex (Reuters)

Cuadrilla Resources has started exploratory drilling for shale gas at its Balcombe site in West Sussex, where the energy firm has been met by anti-fracking protests.

Its first stage will see Cuadrilla drill a 3,000ft vertical well as the company seeks to ascertain if the site contains a commercially viable amount of shale gas that can be extracted.

Campaigners against the shale gas industry, who are camped out at the Balcombe site, tried to block Cuadrilla's vehicles by parking an old fire engine in the middle of the road, but drilling started at around 11:15am on 2 August.

"We have full planning and regulatory approval for this work from the Department for Energy and Climate Change, West Sussex County Council, the Environment Agency, and the Health and Safety Executive," said a spokesman for Cuadrilla about the Balcombe drilling.

Hydraulic fracturing - also known as fracking - is used to extract shale gas. The process involves blasting shale rock, from deep underground, to release the unconventional energy source.

Critics say there is a risk that the chemicals used in the process will leak out into the surrounding area, which could then potentially enter the water supply. They are also concerned that fracking can cause minor tremors.

The shale gas industry's proponents say they are highly regulated, take every precaution during the process, to limit risks. Meanwhile, the British Geological Survey (BGS) conducted an investigation into the effects fracking has on the environment and found that minor tremors equate to no more than a heavy lorry driving past a house.

UK's Shale Gas Potential vs Planning Law

The recent BGS report found that there are enormous shale gas reserves under parts of the north of England.

If it can be extracted, it will give the UK increased energy security as it will be much less reliant on foreign imports to maintain supply. However, the energy industry has already warned that this will not necessarily lead to lower bills for consumers as the gas will still be affected by the global wholesale price.

As it stands, planning responsibility for shale gas extraction projects lies with local councils, but if the potential can be realised then it is likely that the government would officially designate such projects as nationally significant - meaning ministers will take over planning permission powers from local authorities.

The government fears progress on drilling work may be held up by a drawn-out planning process as local authorities look to use their powers to delay or block work from taking place in their areas.

In a bid to appease concerned local communities, the government announced a support package for those living nearby shale gas extraction sites.

Every affected community will get £100,000 and 1% of revenues from the gas that is successfully extracted. Firms must also sign up to a community engagement charter to ensure locals are continuously consulted about any work planned.

However, if communities are not convinced by the funding package and slick public relations of energy firms, they will put pressure on their local elected representatives to halt any attempt at shale gas extraction.

It will likely cause friction between regional authorities and the national government, which wants to make the most of the country's shale gas reserves.